Expanded perlite for a composition comprising plaster

Abstract

A process comprising the following steps: - Supplying raw perlite to a furnace equipped with a flame having a temperature between 900 and 1400 °C, - Bringing said raw perlite into contact with said flame with the formation of a gas flow, - Heating said raw perlite until it reaches a temperature between 700 and 760 °C, forming expanded perlite beads and a fine fraction, - Separating the expanded perlite beads by particle size, collecting said expanded perlite beads and transporting them on an elevator equipped with at least one bucket chain to a receiving silo where said perlite beads are ready for use.

Description

[0001] The present invention relates to a method for transporting expanded perlite beads, to a device and to the use of perlite beads in a composition which includes plaster.

[0002] Perlite is an amorphous volcanic rock, primarily composed of silica, that forms when lava cools rapidly in the presence of water. It belongs to the category of volcanic glasses and has a high water content (approximately 2 to 5% by weight). This characteristic gives it unique properties when subjected to heat treatment.

[0003] High-temperature heat treatment of natural perlite leads to the formation of expanded perlite beads.

[0004] Expanded perlite is a material widely used in industry for its thermal insulation, lightweight, and water-retention properties. Expanded perlite beads have a porous structure that gives them a very low density and high porosity. However, this porous structure, while beneficial for many applications, is also the reason for its fragility.

[0005] Furthermore, depending on the natural origin of the perlite, the applied heat treatment can lead to the formation of perlite beads that are even more fragile compared to other heat-treated perlites, which can complicate their transport and facto reduce their effects when incorporated into products, such as a composition that includes plaster.

[0006] Due to its fragility, the transport of expanded perlite presents a major logistical challenge in the industrial sector. Under the effects of vibrations, shocks, and pressure during handling and transport, expanded perlite tends to disintegrate into fine particles / fragments, resulting in a loss of volume and performance when added to a composition. This degradation can reduce its effectiveness for end applications, particularly lightweight plasters, insulating mortars, or reinforced plasterboard, thus increasing costs related to waste or the need for additional packaging.

[0007] Furthermore, its low density results in a significant occupancy of truck or container volume, further complicating its transport in large quantities and increasing logistical costs. Therefore, transporting expanded perlite to factories or over long distances requires specific methods to minimize mechanical damage and ensure the material's integrity until it reaches the point of use.

[0008] Generally, manufacturers can use Archimedes screws to transport expanded perlite beads, which remain inefficient as they can break the expanded perlite beads.

[0009] Moreover, ilIt is known that pneumatic conveying requires the application of a certain pressure to blow the expanded perlite beads along the container walls. However, this creates friction on the container walls, which breaks some of the expanded perlite beads. A loss of valuable material occurs along the way, impacting production yields and the cost of the industrial installation.

[0010] For these reasons, there is a real need to provide a process for transporting expanded perlite beads by ensuring efficient transport to industrial sites in order to allow use with a large quantity of material, while minimizing as much as possible the losses generated related to the formation of fragments of perlite beads whose low porosity is not advantageous for the user.

[0011] To solve this problem, the present invention provides a method for transporting expanded perlite beads intended for a composition that includes plaster, said method comprising the following steps: Supplying raw perlite to a furnace equipped with a flame located at the bottom of the furnace and having a temperature between 900 and 1400 °C, preferably about 1200 °C, bringing said supplied raw perlite into contact with said flame of said furnace with the formation of an upward gas flow relative to the direction of supply of said raw perlite, heating said raw perlite until it reaches a temperature between 700 and 760 °C, preferably a temperature between 720 and 740 °C, forming expanded perlite beads and a fine fraction, relative to said expanded perlite beads, and carrying said expanded perlite beads and said fine fraction by said gas flow formed towards the upper part of the furnace, located opposite said flame, Particle size separation between said expanded perlite beads and said fine fraction, Collection of said expanded perlite beads and transport thereof on an elevator equipped with at least one bucket chain to a receiving silo where said perlite beads are ready for use.

[0012] The raw perlite is thus supplied to the upper part of the said kiln and reaches the lower part of the kiln to allow contact with the flame.

[0013] The raw perlite is then heated to allow its expansion into perlite beads, which constitute the material of interest. The temperature allows for the desired conversion based on the targeted properties, particularly when added to a composition containing plaster.

[0014] This generates a gas flow, primarily composed of air and combustion gases, which rises to the top of the furnace, carrying with it the expanded perlite beads and the fine fraction. This fine fraction may include fine particles and dust generated during the heating of the raw perlite. It is characterized as being fine relative to the size of the expanded perlite beads.

[0015] The particle size separation stage allows for the recovery of expanded perlite beads on the one hand, and a fine fraction on the other. The perlite beads can then be collected, for example, using a collection hopper.

[0016] Next, the transport is carried out directly, advantageously continuously in the process so as to be able to prepare the perlite beads for their final use.

[0017] It has been observed that using an elevator equipped with at least one bucket chain ensures continuous and stable transport without risk of damaging the perlite beads, which will then reach the receiving silo. Thus, specific quantities of expanded perlite beads can be transported by the elevator to the receiving silo while guaranteeing that the structure of the expanded perlite beads remains intact.

[0018] Thus, the present invention makes it possible to provide a final product directly usable on an industrial site by safely and efficiently providing for the expansion of raw perlite, the transport of expanded perlite beads and advantageously the mixing with a composition intended for civil engineering, construction...

[0019] The final application may include lightweight plasters, insulating mortars or (reinforced) plasterboard or any material that can be mixed with expanded perlite beads.

[0020] This process is therefore particularly advantageous for the user who wishes to integrate all these steps within the same production site.

[0021] The invention makes it possible to transport extremely fragile expanded perlite beads to an industrial site while limiting breakage, while maintaining a high material yield between the raw perlite introduced and the ready-to-use expanded beads, and allowing their controlled integration into a plaster composition.

[0022] The process according to the invention requires little handling and offers improved profitability compared to known processes. Thus, the ratio between the quantity of raw perlite heat-treated and the quantity of perlite beads formed that reach the receiving silo is between 0.89 and 1, preferably between 0.95 and 1. This is particularly remarkable and results in minimal material loss.

[0023] This is particularly advantageous since adding perlite to a final product, such as a plaster-based composition, results in a lightweight material. If the plaster is to be sprayed onto a wall, it is preferable to ensure that a maximum amount of the initially added perlite remains present in the plaster while maintaining its porous and lightweight properties during application. Its activity is thus beneficial, allowing its properties to be fully utilized.

[0024] The challenge is to control all the processing stages of the starting product, in this case, raw perlite, up to its arrival at the receiving silo, in order to allow quality use with the specific needs of the market.

[0025] According to a preferred mode, the supply step is carried out in a supply module which includes a hopper equipped with a rotary valve which is arranged to release a predefined quantity of raw perlite, said hopper being followed by a vibrating wall descending towards the lower part of said furnace and part of which extends into said furnace.

[0026] Preferably, the particle size separation step is carried out in a separation module, part of which is connected to the elevator, preferably by means of a hopper for collecting the expanded perlite beads. The separation module may include a receiving tank for the fine fraction and the gas stream. The separation module may be connected to a collection module that includes a collection hopper for retrieving the expanded perlite beads, which are then directed to a conveying module that includes the elevator equipped with at least one bucket chain and the receiving silo.

[0027] More advantageously, the collection module, which may include the expanded perlite bead collection hopper, is connected to a transport module which includes said elevator equipped with at least one bucket chain and the receiving silo.

[0028] Preferably, the process is implemented so that the transport step of the expanded perlite beads is carried out by means of an elevator equipped with at least one bucket chain extending over at least three transport zones defined in relation to ground level, including a first flat or ascending zone, a second flat zone and a third descending zone, the third zone being connected to the receiving silo.

[0029] In this way, it is possible to carry out the expansion step to form the perlite beads and recover them with all the necessary precautions using the process according to the invention.

[0030] Preferably, the process is implemented so that the transport step of the expanded perlite beads is carried out by means of an elevator equipped with at least one bucket chain extending over four transport zones defined in relation to ground level, including a first flat zone, a second ascending zone, a third flat zone and a fourth descending zone, the fourth zone being connected to the receiving silo.

[0031] Advantageously, said raw perlite has a residence time in said kiln of between 0.1 and 10 seconds, preferably between 0.1 and 8 seconds, more preferably between 0.1 and 5 seconds, corresponding to the time spent in said kiln, preferably until reaching the top, in the upper part thereof.

[0032] This allows for the efficient processing of raw perlite while simultaneously achieving expansion to provide perlite beads with the desired properties.

[0033] More preferably, the heating step of said raw perlite is implemented so that the expanded perlite beads formed and carried by said gas flow to the upper part of the furnace have, upon arrival at the upper part of said furnace, a temperature between 630 and 720 °C, preferably between 640 and 700 °C, more preferably between 645 and 665 °C, preferably at the outlet of said furnace.

[0034] This allows the expanded pearlite beads to be recovered at a cooler state. This ensures slow cooling and controlled expansion of the pearlite beads.

[0035] More advantageously, the raw perlite is supplied in a vertical kiln.

[0036] Thus, the kiln has a lower part which includes the flame and an upper part which allows the kiln to be supplied with raw perlite and which also has an outlet for the flow of gas and the fine fraction which rise, opposite the flame.

[0037] Depending on the preferred method, this separation is carried out using a vortex separator or a cyclone separator. This allows for high-quality particle size separation to recover the perlite beads that constitute the material of interest. This step is advantageous because it preserves the structure of the perlite beads without damaging them.

[0038] In a particularly preferred method, the raw perlite is fed into the furnace in a controlled manner by means of a hopper equipped with a rotary valve. This valve is designed to release a predetermined quantity of raw perlite, which, by the effect of gravity, reaches a descending vibrating wall. A portion of this wall extends into the upper part of the furnace, allowing it to come into contact with the flame. The raw perlite thus reaches the bottom of the furnace where the flame is located.

[0039] Controlling the quantity of perlite ensures a stable process, preferably implemented continuously. This allows for a controlled and regular feeding of the furnace.

[0040] Advantageously, the heating step leads to the formation of said fine fraction whose particle size distribution is less than 90 µm.

[0041] Preferably, the fine fraction has a particle size distribution of less than 90 µm.

[0042] Preferably, the process is implemented so that the step of supplying the raw perlite into the furnace is carried out with a perlite of which at least 70% by weight, preferably at least 80% by weight, more preferably 85% by weight have a particle size distribution greater than 200 µm.

[0043] Even more preferably, the raw perlite supplied should have a moisture content of less than 0.5% by volume. If it is too moist, energy is lost in the kiln and the final product becomes sticky. This is to avoid heat loss and prevent the formation of clumps in the feeding system.

[0044] Selecting the right humidity level allows for proper expansion of the perlite beads.

[0045] Advantageously, said ready-to-use expanded perlite beads also include an amount of non-expanded perlite of less than 0.2% by volume relative to the total volume of said expanded perlite beads.

[0046] By maintaining a quantity of unexpanded perlite below 0.2% by volume, uniformity, optimal insulation, weight reduction and better handling of the expanded perlite beads are guaranteed, thus improving their performance and versatility in various applications.

[0047] More advantageously, said ready-to-use expanded perlite beads comprise an amount of over-expanded perlite of less than 10% by volume relative to the total volume of said expanded perlite beads.

[0048] Limiting the amount of over-expanded perlite to less than 10% ensures mechanical stability, uniform density, optimal insulating properties, increased resistance to moisture and better handling of the final product, thus optimizing its technical performance and durability.

[0049] Preferably, the process is implemented so that the collection of expanded perlite beads provides ready-to-use beads of which at least 75% by weight, preferably 80% by weight, more preferably 85% by weight have a particle size distribution greater than 200 µm.

[0050] This allows us to provide perlite beads that have the best properties, particularly when they are part of a composition that includes plaster.

[0051] According to an advantageous embodiment, the process is implemented such that the expanded perlite bead collection step provides ready-to-use beads of which at least 55% by weight, preferably 60% by weight, have a particle size distribution greater than 0.5 mm. If too large a proportion of the expanded perlite beads has a particle size distribution less than 0.5 mm, the desired effects cannot be guaranteed.

[0052] Advantageously, characterized in that the process is implemented such that the expanded perlite bead collection step provides ready-to-use beads of which less than 15% by weight, preferably less than 10% by weight, have a particle size distribution greater than 1.250 mm. Indeed, if the expanded perlite beads have a particle size distribution that is too coarse, i.e., greater than 1.250 mm (in a larger proportion), they risk causing scratches when they are part of a composition, for example, of plaster, and this composition is applied to a substrate.

[0053] Preferably characterized in that the process is implemented in such a way that the expanded perlite bead collection step provides said expanded perlite beads ready for use with a density between 40 and 80 kg / m³, preferably between 50 and 65 kg / m³.

[0054] Expanded perlite beads with a density between 40 and 80 kg / m³, and preferably between 50 and 65 kg / m³, offer advantages in terms of lightness, mechanical strength, thermal and acoustic insulation, moisture resistance and ease of integration into various industrial and construction applications.

[0055] More preferably, after the transport of said expanded perlite beads to said receiving silo, a volumetric dosing of said expanded perlite beads is carried out to mix them into a composition which includes plaster.

[0056] This allows for an easy-to-implement solution depending on the type of final composition, advantageously plaster. Depending on the final application, the quantities of expanded perlite beads are adjusted to provide a composition with the desired properties.

[0057] Precise volumetric dosing ensures an exact proportion of expanded perlite beads in the plaster mix. This results in consistent and homogeneous properties in the final product, whether it be lightweight plasters, insulating mortars, or reinforced plasterboard. Accurate dosing thus contributes to a higher quality finished material, with optimized performance in terms of weight, thermal insulation, and mechanical strength.

[0058] More preferably, the volumetric titration comprises the following steps: Provision of a boiler which includes within it a rack arranged to move a probe between a minimum position and a maximum position, said minimum position corresponding to a filling level equal to 0% by volume, where said boiler is empty and said maximum position corresponding to a filling level equal to 100% by volume, where said boiler is completely filled with said expanded perlite beads.

[0059] Volumetric dosing with a boiler equipped with a rack and pinion and a probe offers advantages such as dosing accuracy, operational flexibility, mixing efficiency, automation and reproducibility, thus optimizing the quality and performance of plaster and expanded perlite based products.

[0060] Advantageously, said expanded perlite beads are introduced into said boiler in a predetermined quantity, preferably a quantity between 0.5 and 50% by volume relative to the total volume of said boiler, advantageously according to the desired plaster composition, in an automated manner.

[0061] Preferably, the process according to the invention includes a step of adding said expanded and dosed perlite beads to a composition which includes plaster.

[0062] More advantageously, the process is implemented so that the addition of expanded perlite beads to the composition comprising plaster is carried out in such a way as to obtain, when applying said composition to a support, expanded perlite beads of which at least 15% by weight, preferably at least 20% by weight, more preferably at least 30% by weight, advantageously at least 40% by weight remain active, the percentage by weight being defined in relation to the initial quantity of perlite beads included in said composition.

[0063] The advantage of maintaining at least 15% by weight, preferably at least 20% by weight, more preferably at least 30% by weight, advantageously at least 40% by weight of active expanded perlite beads in a composition which includes plaster when applied to a support lies mainly in the optimization of the functional properties of the plaster, coating or final material.

[0064] These expanded perlite beads, known as "active" beads, retain their physical and mechanical properties after mixing with plaster, allowing them to fully perform their role as an improver. In particular, they help reduce the overall density of the mixture, making the plaster lighter and therefore easier to handle and apply to the substrate. This also reduces the weight exerted on structures, a significant advantage for applications such as ceiling plasters, drywall partitions, or structures with limited load-bearing capacity.

[0065] The presence of a significant percentage of active perlite beads also helps maintain excellent thermal and acoustic insulation properties. Thanks to their porous structure and their ability to trap air, these beads limit heat transfer and reduce noise. This improves the thermal and acoustic comfort of buildings where the plaster is applied.

[0066] Finally, this optimal percentage of active beads ensures simplified implementation and homogeneous distribution of the beads in the plaster matrix, avoiding component segregation problems and guaranteeing consistent performance across the entire treated surface.

[0067] More advantageously, said gas stream and said fine fraction which includes fine particles and dust from said furnace are cooled, after the separation step, preferably with a heat exchanger, lowering their temperature to a value between 160 and 190 °C, preferably between 170 and 180 °C, before entering a filter.

[0068] This improves filtration efficiency while protecting downstream equipment. Furthermore, this cooling also optimizes the trapping of fine particles. At lower temperatures, particles are less likely to pass through the filter, thus improving dust collection efficiency.

[0069] Preferably, said process according to the invention comprises passing said fine fraction through said filter, preferably a bag filter, and recovering said fine fraction.

[0070] More preferably, the recovered fine fraction is reintroduced after the separation step.

[0071] More preferably still, the said gas flow generated during the contacting step is drawn in by a fan located at the level of said filter.

[0072] By drawing air directly from the filter, the fan facilitates the trapping of fine particles and dust contained in the gas stream. This ensures that the particles are immediately directed to the filter for capture, thus improving filtration efficiency.

[0073] Other embodiments of the process according to the invention are indicated in the attached claims.

[0074] The invention also relates to a device for transporting expanded perlite beads intended for a composition that includes plaster, said device comprising: A furnace equipped with a flame located at its lower end and having a temperature between 900 and 1400 °C, preferably around 1200 °C, said furnace being arranged to be supplied with raw perlite and arranged to form expanded perlite beads; A supply module comprising a hopper equipped with a rotary valve arranged to release a predetermined quantity of raw perlite, said hopper being followed by a vibrating wall descending towards the lower part of said furnace and part of which extends into said furnace; A particle size separation module arranged to separate expanded perlite beads and a fine fraction; A collection module, preferably comprising a hopper; A transport module connected to the collection module comprising an elevator equipped with at least one bucket chain arranged to transport the expanded perlite beads to a receiving silo.

[0075] According to a preferred mode of the device according to the invention, said transport module comprises at least 3 transport zones: the first zone being flat or (and then) ascending, the second zone being flat and the third zone being descending, all defined with respect to ground level, and in that said first zone is connected to said collection module and in that said third zone is connected to said receiving silo.

[0076] More preferably, said transport module extends over 4 transport zones: the first zone being flat, the second zone being ascending, the third zone being flat and the fourth zone being descending, all defined in relation to ground level, and in that said fourth zone is connected to said receiving silo.

[0077] Preferably, the device includes a volumetric dosing module located after the receiving silo and a mixing module arranged to provide a composition that includes plaster and expanded perlite beads.

[0078] It should be noted that all the characteristics related to the process can be transposed to the device. Thus, all the preceding paragraphs can also be applied to the device.

[0079] Other embodiments of the device according to the invention are indicated in the attached claims.

[0080] The invention also relates to the use of expanded perlite beads supplied according to the process of the present invention in a plaster composition.

[0081] Other embodiments of this use according to the invention are indicated in the attached claims.

[0082] Within the scope of the present invention, expanded perlite beads can be added to a composition intended for civil engineering or construction. Preferably, the expanded perlite beads are part of a composition that includes plaster, which is particularly preferred. It is advantageous to incorporate them into lightweight plasters, insulating mortars, reinforced plasterboard, spray plaster, or any other material whose properties are improved by the presence of the expanded perlite beads according to the invention.

[0083] It should be noted that the expression "composition containing plaster" can be replaced by "plaster composition". The latter may include various additives and formulations known to those skilled in the art.

[0084] In the context of the present invention, the term "fine fraction" refers to a fraction comprising fine particles and dust produced during the heating stage of the raw perlite. This fraction is described as fine relative to the size of the expanded perlite beads.

[0085] Preferably, the process according to the present invention can be implemented using a device that includes at least one oven and several modules.

[0086] A supply module which advantageously includes a hopper equipped with a rotary valve.

[0087] A separation module that preferably includes a tank to receive the fine fraction and the gas stream.

[0088] A collection module which advantageously includes a collection tank for expanded perlite beads.

[0089] A transport module which includes the elevator equipped with at least one bucket chain and the receiving silo.

[0090] The furnace is preferably a vertical furnace comprising a lower section at its base, which is in contact with the ground, and an upper section at the top of the furnace. The lower section houses the flame, which operates at a temperature between 900 and 1400 °C, preferably around 1200 °C.

[0091] Preferably, the supply module includes a hopper equipped with a rotary valve and a downward-moving vibrating wall extending towards the lower part of the furnace, a portion of which extends into the furnace. The hopper is arranged to release a predetermined quantity of raw perlite. The vibrating wall brings the raw perlite into contact with the flame.

[0092] A particle size separation module that allows the separation of expanded perlite beads and a fine fraction.

[0093] A collection module, preferably including a hopper.

[0094] A transport module linked to the collection module comprising an elevator equipped with at least one bucket chain arranged to transport the expanded perlite beads to a receiving silo.

[0095] The said transport module comprises at least 3 transport zones: the first zone being flat or (and then) ascending, the second zone being flat and the third zone being descending, all defined in relation to ground level, and in that the said first zone is connected to the said collection module and in that the said third zone is connected to the said receiving silo.

[0096] A volumetric dosing module allows for mixing, for example, predefining the precise quantity to add to a plaster composition to meet specifications in terms of mechanical properties, while taking into account the final application. This module includes a boiler, a rack and pinion system, and a probe.

[0097] The device according to the invention may also include a volumetric dosing module located after the receiving silo and a mixing module arranged to provide a composition that includes plaster and expanded perlite beads.

[0098] In practice, and according to an embodiment that allows the process according to the invention to be assimilated, a quantity of raw perlite is fed into the hopper of said supply module, and the associated rotary valve is operated automatically according to the quantity of raw perlite to be supplied to said furnace. Thus, when the quantity is released, the raw perlite falls onto the descending vibrating wall to feed the bottom of the furnace (lower part). The flame has a temperature between 900 and 1400 °C, preferably around 1200 °C.

[0099] In this way, the raw perlite comes into contact with the flame, allowing the perlite beads to expand. This contact generates a gas flow that includes air and gases resulting from the combustion of the raw perlite. The raw perlite is heated to a temperature between 700 and 760 °C, preferably between 720 and 740 °C, to facilitate its expansion.

[0100] The generated gas flow rises to the top of the furnace, carrying with it a fine fraction and expanded perlite beads. These expanded perlite beads, upon reaching the top of the furnace, have a temperature between 630 and 720 °C, preferably between 640 and 700 °C, and more preferably between 645 and 665 °C, ideally at the furnace outlet. This is because the higher the perlite beads rise towards the top of the furnace, the more they cool.

[0101] The said fine fraction thus formed, and presented within the framework of the invention, is fine compared to the said expanded perlite beads.

[0102] A particle size separation between the expanded perlite beads and the fine fraction is carried out in the separation module. This separation is advantageously performed with a separator designed to simulate a vortex or with a cyclone separator.

[0103] This allows the recovery of the fine fraction which advantageously has a particle size distribution of less than 90 µm.

[0104] On one side the fine fraction is recovered and on the other the material of interest, the expanded perlite beads.

[0105] Thus, the said expanded perlite beads are collected, for example in a collection hopper.

[0106] Next, transport can be carried out using a forklift equipped with at least one bucket chain. This forklift will ensure careful, stable, and efficient transport to the receiving silo where the perlite pellets are ready for use.

[0107] More specifically and preferably, the elevator equipped with said at least one bucket chain extends over at least 3 transport zones, the first zone being flat or (and then) ascending, the second zone being flat and the third zone being descending, all defined in relation to ground level, and in that said third zone is connected to said receiving silo.

[0108] The perlite beads obtained in the receiving silo exhibit the following characteristics, whether considered individually or in combination: At least 70% by weight, preferably at least 80% by weight, more preferably 85% by weight of said raw perlite supplied has a particle size distribution greater than 200 µm; said raw perlite supplied has a moisture content of less than 0.5% by volume; said ready-to-use expanded perlite beads also comprise an amount of unexpanded perlite less than 0.2% by volume relative to the total volume of said expanded perlite beads; said ready-to-use expanded perlite beads comprise an amount of over-expanded perlite less than 10% by volume relative to the total volume of said expanded perlite beads; at least 75% by weight, preferably 80% by weight, more preferably 85% by weight of said ready-to-use expanded perlite beads have a particle size distribution greater than 200 µm; at least 55% by weight,Preferably, 60% by weight of said ready-to-use expanded perlite beads have a particle size distribution greater than 0.5 mm; less than 15% by weight, preferably less than 10% by weight of said ready-to-use expanded perlite beads have a particle size distribution greater than 1.250 mm; said ready-to-use expanded perlite beads have a density between 40 and 80 kg / m³, preferably between 50 and 65 kg / m³.

[0109] After the expanded perlite beads are transported to the receiving silo, they are volumetrically dosed to be mixed with a composition containing plaster. This volumetric dosing can be carried out in the dosing module, which includes a boiler containing a rack and pinion and a probe. The probe is movable between a minimum position (0% fill of the boiler) and a maximum position (100% fill of the boiler).

[0110] Thus, if 20% by volume is required for 1 ton of plaster, the probe is automatically set to 20% of the boiler's volume to measure and dispense the necessary quantity. Then, the mixture can be prepared with the plaster, the plaster being an optional example.

[0111] If a plaster composition is to include more or less expanded perlite beads, the volumetric dosing module (read the probe) will be automatically configured to dose the next quantity according to the type of composition.

[0112] The volumetric dosing as described in the context of the invention allows the dosage of perlite beads to be adjusted automatically in a flexible and easy manner.

[0113] When perlite beads are dosed and mixed with a plaster composition, it has been found that at least 15% by weight of said expanded perlite beads remain active in said composition when applied to a support, the percentage by weight being defined in relation to the initial quantity of perlite beads in said composition which includes plaster.

[0114] Regarding the fine fraction separated above, it is advantageously drawn off by a fan located at a filter, preferably a bag filter. This recovered and filtered fine fraction is then reintroduced after the separation step.

[0115] It should be noted that the modules presented above may be indicated in the process according to the invention, if necessary, within the scope of the present invention.

[0116] The articles "a" and "an" are used here to refer to one or more of one (i.e., at least one) of the grammatical objects of the article and can be replaced by an article that denotes a plural such as "at least 2", "at least 3", "several", etc.

[0117] The expressions "in one embodiment," "according to one embodiment," and similar terms generally mean that the particular feature, structure, or characteristic referred to in the expression is included in at least one embodiment of this disclosure, and may be included in more than one embodiment of this disclosure. It is important to note that such expressions do not necessarily refer to the same embodiment.

[0118] If the text indicates that a component or feature "may" or "could" be included or have a feature, it is not necessary that this particular component or feature be included or have the feature.

[0119] If it appears here, the term "comprising" or "containing" and derivatives thereof are not intended to exclude the presence of any additional component, step, or procedure, whether or not disclosed herein. For the avoidance of doubt, the term "comprising" may include any additional element / additive, adjuvant, or compound unless otherwise specified. By contrast, the term "essentially consisting of," if it appears here, excludes from the scope of any subsequent quotation any other component, step, or procedure except those not essential to operability, and the term "consisting of," if used, excludes any component, step, or procedure not specifically defined or indicated. The terms "or" and "and / or," unless otherwise specified, refer to the members indicated individually as well as in any combination. For example, the expression A and / or B refers to A alone, B alone, or A and B.Furthermore, the term and any equivalent to "comprising" can be replaced by "consisting of".

[0120] It is understood that the present invention is in no way limited to the embodiments described above and that many modifications can be made to it without departing from the scope of the attached claims.

Claims

1. A method for transporting expanded perlite beads intended for use in a composition comprising plaster, said method comprising the following steps: - Supplying raw perlite to a furnace equipped with a flame located at the bottom of the furnace and having a temperature between 900 and 1400 °C, preferably about 1200 °C, - Bringing said supplied raw perlite into contact with said flame of said furnace with the formation of an upward gas flow relative to the direction of supply of said raw perlite, - Heating said raw perlite until it reaches a temperature between 700 and 760 °C, preferably a temperature between 720 and 740 °C, forming expanded perlite beads and a fine fraction, relative to said expanded perlite beads, and carrying these beads by said gas flow towards the top of the furnace, located opposite said flame,- Particle size separation between said expanded perlite beads and said fine fraction, - Collection of said expanded perlite beads and transport thereof on an elevator equipped with at least one bucket chain to a receiving silo where said perlite beads are ready for use.

2. Method according to claim 1, the method is implemented so that the transport step of the expanded perlite beads is carried out by means of an elevator equipped with at least one bucket chain extending over at least three transport zones defined in relation to ground level, including a first flat or ascending zone, a second flat zone and a third descending zone, the third zone being connected to the receiving silo.

3. A method according to any one of the preceding claims, characterized in that, the heating stage of said raw perlite is implemented in such a way that the expanded perlite beads formed and carried by said gas flow to the upper part of the furnace have, upon arrival at the upper part of said furnace, a temperature between 630 and 720 °C, preferably between 640 and 700 °C, more preferably between 645 and 665 °C, preferably at the exit of said furnace.

4. A method according to any one of the preceding claims, characterized in that said separation is carried out with a separator designed to simulate a vortex or with a cyclone separator.

5. A method according to any one of the preceding claims, characterized in that the heating step leads to the formation of said fine fraction whose particle size distribution is less than 90 µm.

6. A method according to any one of the preceding claims, characterized in that, the process is implemented in such a way that the collection of expanded perlite beads provides ready-to-use beads of which at least 75% by weight, preferably 80% by weight, more preferably 85% by weight have a particle size distribution greater than 200 µm.

7. A method according to any one of the preceding claims, characterized in that The process is implemented in such a way that the expanded perlite bead collection step provides ready-to-use beads of which at least 55% by weight, preferably 60% by weight, have a particle size distribution greater than 0.5 mm.

8. A method according to any one of the preceding claims, characterized in that The process is implemented so that the expanded perlite bead collection step provides ready-to-use beads of which less than 15% by weight, preferably less than 10% by weight, have a particle size distribution greater than 1.250 mm.

9. A method according to any one of the preceding claims, characterized in that , after the transport of said expanded perlite beads to said receiving silo, a volumetric dosing of said expanded perlite beads is carried out to mix them into a composition which includes plaster.

10. A method according to any one of the preceding claims, characterized in that said volumetric dosing includes the following steps: - Provision of a boiler which includes within it a rack arranged to move a probe between a minimum position and a maximum position, said minimum position corresponding to a filling level equal to 0% by volume, where said boiler is empty, and said maximum position corresponding to a filling level equal to 100% by volume, where said boiler is completely filled with said expanded perlite beads.

11. A method according to any one of the preceding claims, characterized in thatsaid gas stream and said fine fraction which includes fine particles and dust from said furnace are cooled, after the separation step, preferably with a heat exchanger, lowering their temperature to a value between 160 and 190 °C, preferably between 170 and 180 °C, before entering a filter.

12. Method according to claim 11, including passing said fine fraction through said filter, preferably a bag filter, and recovering said fine fraction.

13. Method according to claim 12, characterized in that said fine fraction recovered is reintroduced after said separation step.

14. Device for conveying expanded perlite beads intended for a composition comprising plaster according to the process described in any one of the preceding claims, said device comprising: - A furnace equipped with a flame located in its lower part and having a temperature between 900 and 1400 °C, preferably about 1200 °C, said furnace being arranged to be supplied with raw perlite and arranged to form expanded perlite beads, - A supply module comprising a hopper equipped with a rotary valve arranged to release a predetermined quantity of raw perlite, said hopper being followed by a vibrating wall extending downwards towards the lower part of said furnace and a portion of which extends into said furnace, - A particle size separation module arranged to separate expanded perlite beads and a fine fraction, - A collection module, preferably comprising a hopper,- A transport module connected to the collection module, comprising an elevator equipped with at least one bucket chain arranged to transport the expanded perlite beads to a receiving silo.

15. Device according to claim 14, wherein said transport module comprises at least 3 transport zones: the first zone being flat or (and then) ascending, the second zone being flat and the third zone being descending, all defined with respect to ground level, and in that said first zone is connected to said collection module and in that said third zone is connected to said receiving silo.

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